Speaker Biography: Ben Wootten: Graduated from St. Olaf College with a B.A. in Physics and Mathematics in 2011. He is now a graduate student at the University of Iowa researching edge emitting superluminescent diodes for optical chemical sensors.

Summary: High power, 2-2.5 μm light emitting diodes are important light sources for compact optical point sensing of biomolecules such as glucose. The 2-2.5 um absorption window is particularly important for measurement of biomolecules in aqueous environments both because water absorption has a relative minimum and because many important biomolecules have characteristic absorption spectra in that wavelength range. A broadband light source is needed to obtain a spectrally resolved optical absorption spectrum of the matrix containing the biomolecule, which is a prerequisite for robust calibration models to determine of the presence and concentration of a particular biomolecule in the complex matrix. Previous approaches to high brightness sources include tunable GaInAsSb/AlGaAsSb quantum well lasers, which have very high power, but are complex in that they require moving parts and external cavities. Mesa surface light-emitting diodes from GaInAsSb/GaSb have also been demonstrated, but output powers are low (300 μW upper hemisphere at room temperature), which degrades the signal-to-noise of the measurement. Here we demonstrate edgelight-emitting diodes from GaInAsSb/AlGaAsSb quantum well heterostructures with output powers exceeding 6 mW when integrated into an f/1 acceptance cone. We present evidence that broadband output is amplified by stimulated emission without lasing, i.e. superluminescent.... Read Full Abstract [PDF]